1. Field of Invention
The present invention relates to an exhaust gas recirculation (EGR) system that recirculates an exhaust gas to an engine, and more particularly, to an exhaust gas condensate control method that can keep the components of an EGR system safe against the danger of corrosion by preventing possibility of generation of condensate from an exhaust gas flowing through an EGR line, and an exhaust gas recirculation system using the method.
2. Description of Related Art
In general, when an exhaust gas recirculation (EGR) system is used, the intake air supplied to an engine is compressed by operating a turbo charger with an exhaust gas discharged to the outside from the engine while some of the exhaust gas is supplied back to the engine, such that engine performance can be improved.
The EGR system can be classified into an HP (High Pressure)-EGR type that takes out and uses an exhaust gas (or referred to as an EGR gas) before the turbo charger and an LP (Low Pressure)-EGR type that takes out and uses an exhaust gas behind the turbo charger.
In general, the EGR system is applied to vehicles in a combination of the HP-EGR and the LP-EGR.
The HP-EGR is a type that takes out some of the exhaust gas out of an exhaust manifold before the exhaust gas flowing into a turbo charger and directly supplies the exhaust gas to an intake manifold, whereas the LP-EGR is a type that sends some of an exhaust gas, which has passed through a turbo charger and a diesel particulate filter (DPF, a catalytic filter) after out of an exhaust manifold, to the front end of a compressor of the turbo charger and then allows the exhaust gas mixing with an intake air and flowing to an intake manifold.
Therefore, unlike the HP-EGR, the LP-EGR can reduce generation of nitride oxide by using relatively clean exhaust gas with pollutants filtered through the DPF at low pressure/low temperature, and the exhaust gas is supplied to the front end of the compressor of the turbo charger, such that distribution performance of the exhaust gas can be considerably improved.
In particular, when an EGR system implements only the LP-EGR without the HP-EGR, all of the exhaust gas can be used in the turbo charger, such that efficiency of the turbo charger can be significantly increased.
Although the EGR system has various advantages as described above, it is necessarily equipped with an EGR valve, an EGR cooler, a turbo charger, and an intercooler, such that the configuration of an engine room becomes necessarily complicated.
These necessary components, particularly the turbo charger for compressing an intake air and the intercooler for decreasing temperature of excessive gas mixture, necessarily cause phase change of the exhaust gas and the phase change of the exhaust gas necessarily leads to condensation.
The condensate produced in the EGR system accumulates in the turbo charger and the intercooler, which may be corroded, such that corrosion is necessarily accelerated particularly at the compressor of the turbo charger and the outlet of the intercooler.
The acceleration of corrosion in the turbo charger and the intercooler is, unlike the HP-EGR, more deteriorative for the LP-EGR type of EGR system necessarily equipped with the turbo charger and the intercooler, which may be a factor that largely decreases actual applicability of the LP-EGR type of EGR system to vehicles.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.